The present invention relates to light emitting apparatus for motor vehicles, of the kind comprising lighting or indicating apparatus for illumination and/or signalling purposes.
Current practice in the automobile industry is to assemble together in a single housing several different lighting or indicating functions, so as to simplify the electric wiring that serves these various functions. Each function includes a light source, a reflector, and often a cover glass, these various components being arranged to provide a beam for illumination or signalling purposes, the geometric and photometric characteristics of which must be in conformity with various legal requirements.
Each of these functions thus necessitates provision of a minimum volume for fitting it within a particular lighting or indicating apparatus. However, the space available for fitting such apparatus tends to be more and more reduced as automobile design evolves, and this is true both at the front and at the rear of a modern motor vehicle. In this connection, aerodynamic requirements and the ideas imposed by stylists lead to forms which are often very different from those which would result only from technical considerations. As a result, in many cases, the space available for grouping together these functions in a common housing is insufficient, and it is therefore necessary to distribute various functions in various different casings, which leads to an increase in costs and also in manufacturing time for fitting wiring and assembling the vehicle generally.
Various attempts have already been made to overcome these problems by making use of light guides. This prior art will now be explained, with reference to FIGS. 1 to 4 of the accompanying drawings, to which reference is now made. FIGS. 1 to 4 show one example of a known apparatus of the kind mentioned above. FIG. 1 shows a lamp 1 which is fitted within a reflector 2 for concentrating light rays emitted by the lamp 1 on the input face 3 of a set of optical fibres or a set of groups of optical fibres 4. The reflector 2 is for example of the elliptical type, the light source of the lamp 1 being placed close to a first focus of the reflector 2. The faces 3 are disposed close to the second focus of the reflector 2. The output faces 5 of the optical fibres 4 are coupled to the input faces 6 of light guides 7.
The light guides 7 in this example are so configured that they form a circular shape, and they are for example so arranged that they surround the front perimeter of a dipped or passing beam headlight. The light guides 7 are for example of the kind which are described in German published patent specification No. DE 41 29094A. As can be seen in FIG. 2 of the present Application, the light guides have a substantially flat face 8 for reflection of the light, and a cylindrical or toroidal face 9 for distributing the light. The face 8 consists of a succession of prisms which pass on the light rays that are propagated within the guide towards the face 9 (FIG. 3), from which they are emitted in the form of an output beam consisting of substantially parallel light rays, as can be seen in FIG. 4. The output beam may for example serve for a sidelight function within a headlight.
Such a solution is particularly cumbersome, especially since it makes it necessary to provide a light source such as a halogen lamp, an elliptical reflector, a flexible bundle of optical fibres, and a rigid light guide made of glass or plastics material. In addition, there is always an empty space between the two ends of the light guide through which the light is injected into the guide, and this empty space is detrimental to the appearance of the resulting assembly. In addition, this arrangement does not enable shapes to be provided that have sharp angles, because the propagation of the light within the light guide would be interrupted by the angles.
Another solution could consist in replacing the light guide 7 by a fluorescent tube. This arrangement is less cumbersome and does enable sharper angles to be used, but it does however still leave an empty space between its two ends.
Within the context of the foregoing, an object of the present invention is to propose a lighting or indicating apparatus which enables a lighting and indicating function to be easily incorporated in a headlight, the said lighting or indicating apparatus being also easy to assemble, reliable in operation, and having photometric performance that conforms with legal requirements. A further object is to provide such an apparatus which is less cumbersome and which is easily adaptable to the demands of stylists, so that it can have any appearance whatever from the aesthetic point of view.
The invention is accordingly directed to lighting or indicating apparatus for a motor vehicle, comprising at least one light guide associated with at least one light source for transporting light rays emitted from the light source and entering the light guide through an input face thereof, passing to an output face of the light guide via an intermediate section for transporting the light rays.
According to the invention, the input face of the light guide is defined between two closed lines delimiting a continuous internal contour and a continuous external contour, and the output face is defined between two closed lines delimiting a continuous internal contour and a continuous external contour.
According to a preferred feature of the invention, the intermediate section consists of a block of transparent material defining a continuous volume between the input face and output face.
Preferably, the light guide is associated with a plurality of light sources.
In some embodiments, the light sources are in the form of at least one incandescent lamp. In that case, at least one optical device is associated with the incandescent lamp for converting the light rays emitted from the incandescent lamp into a beam of parallel rays, and the input face of the light guide, facing the lamp, is flat.
In another version, the incandescent lamp is disposed directly behind the input face, and the input face is convex.
In other embodiments, the light sources consist of at least one light emitting diode (LED). In this case, it can be arranged that:
the light emitting diode is disposed directly behind the input face, the input face being convex; and/or
at least one optical device is associated with the light emitting diode for spreading the light flux emitted by the light emitting diode homogeneously in all directions parallel to an optical axis parallel to the optical axis of the light guide, and the input face facing the light emitting diode is generally flat and includes Fresnel prisms.
These various embodiments are applicable where the lighting or indicating apparatus has several light guides nested one within another. It may also be provided that the input faces of the light guides are situated in the vicinity of a common entry plane, and/or that the output faces of the light guides are situated in the vicinity of a common exit plane.
Further features and advantages of the present invention will appear more clearly on a reading of the following detailed description of some preferred embodiments of the invention, which is given by way of non-limiting example only and with reference to the accompanying drawings.